Add a new owner: Agency >Add owner
For more information about setting up a (new) owner please see: Adding Owners and assigning them to a Property

Assign the property to the new owner under: Properties > Edit > Go > section Owner.
This will automatically unassign the old owner from the property.

In order to transfer existing bookings to the new owner go to Agency > Edit Owner > Edit (to the right of the owner) > section Payment Details > sub-section Commission settings. Click on the Update commission on bookings link and select the dates you would like to update the existing bookings from. 

You can either select Arrival / Departure / Booking date.
Arrival date: All bookings with an Arrival date during the selected period will be allocated to the new owner.

Departure date: All bookings with a Departure date during the selected period will be allocated to the new owner.

Booking date: All bookings entered into the system (having been booked) during the selected period will be allocated to the new owner.

Once the existing bookings have been updated the old owner should not have any payments due, which are dated after the selected period in Step 2.
To check this go into the statement of the old owner 

Agency > Commission statement > cog on the right hand side of the old owner > Statement

Should there still be entries in the statement that should be now listing in the new owner statement go into the referenced booking and make the required changes there.
This will automatically update the statement.

Archive the old owner, by going to Agency > Edit owner > Edit.
Should you see a message that there are still funds allocated to the owner, you will need to go through the owner statement, find the outstanding payments and process them.
The owed funds link leads directly to the statement of the owner.